Abrasive cleansers have been known for some time and are now common hard surface cleansers used in homes and institutions. Even more than a century ago, simple dry scouring powders such as Bon Ami® were in the marketplace. Eventually liquid abrasive cleansers emerged, giving the consumer the convenience of a “pre-wetted” abrasive material rather than a dry and often dusty powder. Such liquid abrasives, sometimes called cream or crème cleansers, include all-purpose hard surface cleansers and specialty cleansers such as metal and automobile polishes. Early examples of liquid cleansers included silica based abrasive cleansers, cleansers with clay thickeners, and stearate soap thickened slurries described in U.S. Pat. Nos. 3,985,668, 4,005,027 and 4,051,056 (Hartman), U.S. Pat. No. 4,352,678 (Jones, et al.), and U.S. Pat. No. 4,240,919 (Chapman). Much of this early technology incorporating insoluble abrasives gave way to more modern liquid cleansers with dissolvable or so-called “soft” abrasives. These products often employed calcium carbonate as the abrasive, with the amount of abrasive positioned very high to promote formula stability and to optimize cleaning performance. In spite of the high abrasive content, liquid abrasive cleansers had serious settling problems, often resulting in separation of a free liquid layer residing at the top of the product and a compacted sediment layer at the bottom. Such instability, or syneresis, is problematic for the end-user. Shaking of the liquid product is required prior to each use, and if the compacting of the sedimentary abrasive is severe, even shaking cannot restore the homogeneity of the abrasive suspension. Often the consumer doesn't read the label instructions to “shake before use” or otherwise doesn't think to shake the contents, only to be surprised to find clear thin liquid dispensed from the bottle of abrasive cleanser. Furthermore, none of these high weight percent abrasive suspensions were amenable to spraying through conventional non-aerosol trigger sprayers. These heavy suspensions, often comprising greater than 50 wt. % abrasives, are invariably packed in deformable plastic bottles equipped with closure comprising hinged lid and orifice. With these high abrasive content cream cleansers, the consumer has no choice but to purchase the product in this conventional package and to dispense it by “squirting” the product out through an orifice in the closure.
Many improvements to liquid abrasive cleansers have been described over the years. For example, U.S. Pat. No. 4,704,222 (Smith) discloses a gelled abrasive detergent composition comprising 25%-85% abrasive in a gel matrix of low MW polyethylene glycol and anionic surfactant. The composition also includes a polysulfonic acid that is believed to lubricate the abrasive particles rubbing against the surface to be cleaned, making the manual cleaning process easier.
U.S. Pat. No. 4,869,842 (Denis, et al.) describes an abrasive cleanser with improved degreasing performance through use of non-polar degreasing solvents. Allan also describes the use of degreasing hydrocarbon solvents in abrasive cleansers in PCT application WO98/49261.
U.S. Pat. No. 5,470,499 (Choy, et al.), U.S. Pat. No. 5,529,711 (Brodbeck, et al.), and U.S. Pat. No. 5,827,810 (Brodbeck, et al.) describe bleach-containing abrasive cleansers with improved cleaning performance, improved rinsing, and improved physical stability through use of a high-molecular weight cross-linked polyacrylate polymer.
U.S. Pat. No. 5,821,214 (Weibel) describes an improved liquid abrasive cleanser comprising very high molecular weight cross-linked polyacrylates along with smectite clays for stability.
U.S. Pat. No. 6,511,953 (Fontana, et al.) describes an abrasive cleanser with improved cleaning performance comprising both a nonionic surfactant and a sulfate anionic surfactant.
Very little is known regarding “sprayable” abrasive liquid cleansers. As mentioned, conventional aqueous-based cream cleansers having >50 wt. % abrasives are impossible to spray through a standard trigger sprayer. If a liquid abrasive cleanser even pumps into a standard manual trigger sprayer assembly, nothing is known about controlling the spray pattern of the product emanating from the trigger sprayer nozzle.
U.S. Pat. No. 6,378,786 (Beeston, et al.) discloses an abrasive composition that is claimed sprayable. However, the composition must be sprayed through a “pre-compression” trigger sprayer that is also disclosed in the reference. Pre-compression sprayers give a “burst” spray (single pressure), made possible when pressure in an inner chamber reaches a critical level set by a pre-compression spring. Such sprayers were pioneered by Piero Battegazzore of Guala S.p.A. in Italy (see e.g. U.S. Pat. No. 5,156,304, Battegazzore). The sprayable compositions disclosed in '786 reflect the necessary lowering of abrasive levels to make sprayability at least achievable, (e.g. 10 wt. % chalk, or 10 wt. % diatomaceous earth, rather than >50 wt. % calcite as typical in cream cleansers), yet the compositions nevertheless require a pre-compression burst trigger sprayer (e.g. a Guala sprayer) to make the compositions truly “sprayable.”
U.S. Pat. No. 4,797,231 (Schumann, et al.) discloses a machine dishwashing polishing detergent that is, in a strict sense, sprayable, albeit through the electrically powered mechanical pump and spray jets of a dishwashing machine. The compositions comprise silica and/or alumina polishing particles that are water insoluble, various anionic and amphoteric surfactants, and a fat soluble solvent that optionally may include solvents like limonene, glycol ethers, or polyethylene glycol of molecular weight from about 200,000 to 4,000,000. Although these compositions have suspended particles (i.e. the polishing alumina and/or silica of the particle size found in toothpastes), the compositions “spray” only because of the powerful mechanical pressures achieved in mechanical dishwashing machines and the very fine particle size of the polishing ingredients.
Lastly, Konishi, et al. discloses stable, shear-thinning liquid abrasive cleanser compositions comprising calcium carbonate and non-crosslinked, hydrophobically modified, associative thickeners in U.S. Patent Application Publication 2010/0197557. However, even through the disclosed compositions are phase stable, shear-thinning and show a re-thickening to cling on vertical surfaces, their dispensation remains practical only through the orifice provided in the closure of a standard squirt-bottle package.
In spite of the developments seen over many years, liquid abrasive cleansers still have problems with cleaning performance, phase stability, rinseability, and dispensation, with no teaching as to how to optimize these characteristics while balancing cost-of-goods. There are no high-performance liquid abrasive cleansers described in the prior art that show shear-thinning capability such that they can be easily sprayed from a standard manually-pumped trigger-sprayer package. To date, cream cleansers built with high enough abrasive content to be effective at cleaning remain precariously unstable in storage and unable to be sprayed through an ordinary non-aerosol trigger sprayer. Since there is such little known about sprayable liquid abrasive cleansers in general, it comes as no surprise that there is no prior art teaching how to control the spray pattern of a manually sprayed liquid abrasive cleanser.
For these reasons there is still a need to explore new combinations of surfactant, polymer, and abrasive ingredients that may provide for a low cost liquid abrasive cleanser that shows superior cleaning performance, cleaner rinsing, storage stability, and reliable dispensing. Of ultimate need is an aqueous, liquid abrasive cleanser having not only these attributes, but also the ability to be sprayed from an inexpensive standard non-aerosol spray bottle such as a trigger sprayer package, with control over the effluent spray pattern.